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Lecture 6

HKIN 215 Lecture Notes - Lecture 6: Muscle Spindle, Proprioception, Dermis

5 pages85 viewsFall 2017

Human Kinetics
Course Code
HKIN 215
Dr. Melanie Lam

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Ch 6 Sensory components of motor control
Sensation of Touch
- Many skills require manually manipulating objects/people
Mechanoreceptors in the skin
- Dermis layer
- Relays info to brain
Tactile info in motor control
- Compare tactile feedback in fingertips before and after anesthetization of fingers
- Tactile sensory info influences:
o Movement accuracy
o Movement consistency
o Movement timing
o Movement force adjustments
o Estimates of movement distance
Movement accuracy
- When tactile info is removed, accuracy decreases
- Rao and Gordon
o Pointing movements
o Remove vision to focus on tactile sensation
o Subjects hand guided to one of 16 targets reference movement
o Subject asked to move hand to remembered location test location
o Different amounts of tactile feedback in each condition
o Directional error: side to side (lateral)
o More error with no fingertip contact
o Gain error: error in direction of movement
Movement consistency
- Analyzed consistency of movement in typing with and without tactile feedback
- Less consistency with no touch sensation
- Typing task
Movement timing
- Internal timing is task specific
- Each touch sensation in tapping allows someone to keep proper timing
- Would Velcro help circle drawing because of tactile feedback?
o Yes, comparable results to tapping
Movement force adjustments
- Raise puck 20 cm, measuring force used to produce movement in those with/without tactile feedback
- Healthy controls use less force to pick up objects
- Patients grip harder to lift it since they have no tactile feedback
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Estimates of movement distance
- Ability to estimate a particular distance is compromised
Know evidence to support claims
- Information arises from within the body
o Joint position
o Muscle force
o Orientation of body in space
- Sensory neurons found in muscles, tendons, ligaments, joints
Muscle spindles
- Found in belly of muscle
- 1a axons wrap around central portion of intrafusal fibres
- Function:
o Detect muscle length how much muscle is being stretched
o Detect velocity change how fast muscle is stretched
- Protects you from overstretching/stretching too fast
Golgi-tendon organs (GTOs)
- Found in tendons of muscles
- Function:
o Detect tension in muscle
- Protect you from creating too much force
Joint receptors
- Found in joint capsules and ligaments
- Function:
o Respond to changes in force and rotation applied to joint
o Changes in joint movement angle
Techniques to investigate the role of proprioception in motor control
- Deafferentation removes some proprioception
Surgical deafferentation: humans
- Location proprioceptive feedback not needed for position
- Important for distance
Sensory neuropathy graph
- Y axis constant error
- Normal individuals don’t have much error in different environments
- Deafferented individuals
o Similar to normal with vision
o Undershoots target without vision
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